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A structural feature of particular interest in order to get a better understanding of tissue perfusion is the way a pattern of growing vessels fills the available space. To address this point, we have developed automatic image analysis methods allowing a quantitative evaluation of several parameters (fractal dimension, lacunarity and nonfractal order–disorder parameters, such as positional, topological and orientational order) characterizing the level of spatial order/disorder exhibited by the vascular network of the CAM in basal conditions and after treatment for 96 h with an angiogenic cytokine, such as fibroblast growth factor-2 (FGF-2), or with an angiostatic molecule, such as vinblastine

Prolactin (PRL) granules can be isolated from the anterior pituitary gland of adult cows in nearly 50% yield by use of a procedure previously developed for the fractionation of the rat pituitary. Treatment of the isolated bovine granules with 0.2% Lubrol PX results in the solubilization of most membranes present in the fraction but has only a limited effect on the matrices, which remain aggregated and can be recovered and purified by gradient centrifugation . These membraneless PRL granules, studied in detail by morphological and biochemical techniques, were found to contain only small amounts of contaminants (primarily growth hormone granules and small membrane fragments) . SIDS polyacrylamide gel electrophoresis revealed that, in comparison with other fractions isolated from the bovine pituitary, the membraneless granules have a simpler polypeptide composition including PRL (-85%), growth hormone (-8%), as well as ---13 minor bands with apparent mol wt ranging from 80,000 to 45,000 . Many of these minor bands are accounted for by glycoproteins, as revealed by their binding of ' 25 1-concanavalin A, and two of these are also stained blue by the stains-all procedure, a reaction specific for acidic glycoconjugates. Chemical analyses of the membraneless granule fraction revealed the presence of a heterogeneous mixture of complex carbohydrates . Among glycosaminoglycans, the major component is heparan sulfate, while hyaluronic acid and chondroitin sulfate are present in smaller amounts. Moreover, some of the glycoproteins are sulfated and account for over 50% of the nondialyzable "S radioactivity found in the fraction isolated from labeled slices . Although the concentration of glycosaminoglycans and glycoproteins is relatively low in membraneless granules, the possibility that their presence in the fraction is largely due to cross-contamination and/or artifactual adsorption could be excluded on two grounds. These are: (a) electron microscope radioautography of preparations obtained from ["S]sulfate-and D-[6-3H]glucosamine-labeled slices showed a significant labeling of PRL granules in both intact cells and membraneless granule pellets, and (b) a mixing experiment showed that membraneless granules contain very little macromolecular sulfate radioactivity adsorbed from the soluble glycoconjugates present in the pituitary homogenate .Experimental evidence obtained during the last several years clearly indicates that macromolecular carbohydrates are components of secretory granules not only in cell systems which are specialized for their secretion, but also in many others whose main exported products are of a different nature (e .g., amines and nonglycosylated proteins and peptides) (l0, 19). The function of these minor components is still poorly defined. 260Recently, however, there has been considerable interest in these macromolecules since it has been proposed that they might be involved in the packaging of secretion products (21) . This process, which occurs in the Golgi complex, results in the organizatio...

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